In cutting and grinding processes, oils for cutting and grinding are generally used. Most important functions required for oils for cutting and grinding are lubricating and cooling actions, which can extend the life of the tool used for the processing, improve the finished surface precision of the worked products, raise production efficiency and increase productivity. In conventional cutting and grinding processes, a relatively larger amount of cutting and grinding oils are supplied to points to be processed. However, recently, as interest in environmental problems grow, there are pointed out problems such as waste, environmental sanitation, and energy conservation to oils for cutting and grinding which are effective for production efficiency. In recent years, studies are underway on dry processes for cutting process, grinding process and the like as environmentally friendly methods for metalworking processes. When cutting and grinding processes are conducted in a dry condition, the above environmental problems are reduced but it is not possible to obtain performance such as lubricity and cooling property which are required for oils for cutting and grinding.
It is therefore necessary to cool the processing point, for example, by spraying compressed cooling air or the like. However, since a completely dry process lacks lubricity between processing tool and a material to be processed, a very small amount of lubricating oil is supplied. Examples of working methods include a processing method for nonferrous metal (for example, see Patent Document 1). If conventionally known metalworking oil compositions (for example, see Patent Document 2) is used for processing ferrous material, such problems occur that dew condensation water is formed to generate rust. Therefore, it is not possible to apply these oil compositions to cooling air processing or mist cutting processing. There has been proposed a metalworking oil composition having high antirust property (for example, see Patent Document 3). There has also been proposed a metalworking oil composition comprising phosphatidyl choline compound (for example, see Patent Document 4). As for these metalworking oils, a new working oil which is capable of further improving workability, extending the life span of the instrument and reducing the amount of oil to be supplied is desired in view of increasing the productivity and/or saving energy.
Patent Document 1 JP-A-2001-239437
Patent Document 2 JP-A-2000-256688
Patent Document 3 JP-A-2004-300317
Patent Document 4 JP-A-09-57537